1. Field of the Invention
This invention relates to the stranding device of a stranding machine for electric wires and the like.
2. Description of the Prior Art
Conventional stranding machines have been constructed as shown in FIG. 1, in which a capstan b is driven by a driving shaft a, a flyer c is also driven by the driving shaft a, and a drum e is also driven by the driving shaft a through a stepless transmission device d. In the above prior art device, a number of fine wires f pass through the capstan b and are stranded when passing through the flyer c rotating around a winding drum e, and are wound onto the winding drum e. In FIG. 1, g is a motor, h is a transmission gear and i is an endless screw shaft for horizontal reciprocating motion of the winding drum.
In such a stranding machine as above, the winding drum is generally of a large mass, the diameter of which is sometimes larger than 600 mm, on which stranded wire is wound repeatedly, making the total weight very large. As a result, the stepless transmission gear is subject to a certain amount of inertia force when it reduces the rotational speed of the winding drum gradually in accordance with the necessity to keep the pitch of the stranded wire constant when the diameter of winding increases as the strand is wound. Therefore the stepless transmission gear itself necessarily becomes larger and more robust, so that a 2 to 4% rotating motion ratio is the limit in the case of a friction wheel, or an expensive arrangement is necessary in the case of electric or hydraulic drives, as well as the requirement of special attention for maintenance.